Fluoroolefins, and in particular F-1233zdE, are compounds of major interest for refrigeration and air-conditioning systems, given the new environmental regulations.
It is known practice to produce hydrofluoroolefins such as F-1233zdE by fluorination of hydrochloroolefins or chlorohydrocarbons in particular. This fluorination is generally a fluorination using hydrofluoric acid as fluorinating agent.
Among the routes for obtaining F-1233zdE, it is in particular known practice to use F-240fa (1,1,1,3,3-pentachloropropane) as starting compound. Reference is made, for example, to U.S. Pat. No. 8,704,017 in this regard, which describes a process of liquid-phase fluorination in the absence of catalyst but requiring several reactors in series and/or stirring of the reaction medium to counter the low degree of conversion.
US 2014/0 221 704 teaches the low miscibility between F-240fa and hydrogen fluoride, and proposes the addition of a phase-transfer agent to the reaction medium to solve this problem.
US 2013/0 211 154 suggests increasing the pressure in the reaction medium to improve the degree of conversion of F-240fa.
Another possible process is the liquid-phase fluorination of F-1230za, in the absence of catalyst and under much less severe conditions, this olefinic starting material not having these difficulties of low degree of conversion.
However, it is known that a liquid-phase fluorination process may generate several undesired compounds such as oligomeric compounds, products of high boiling point, toxic or corrosive compounds, or, more generally, impurities that are difficult to separate out. In particular, these oligomeric compounds have the consequence of reducing the efficiency of the fluorination process and must be separated out by a purge, in a continuous system or in a batch system, obtained from the reactor and retreated. Compounds of high boiling point may also prevent the reaction.
The harmful effects of impurities on fluorination processes were also observed in the abovementioned reaction of F-1230za.
Stabilization of tetrachloropropenes with inhibitors, generally antioxidants, is taught in US 2012/0 226 081, US 2012/0 190 902 or US 2014/0 213 831. These inhibitors prevent the formation of oxygenated impurities, mainly phosgene which is toxic, during the phases of transportation and storage. However, the impact of these impurities in a liquid-phase fluorination process is not described.
It is desirable to be able to produce F-1233zdE under good yield conditions on an industrial scale using a process that is simple to perform, especially in the liquid phase and in the absence of catalyst, which allows an improvement in the yield and/or which does not present any difficulties in terms of separating out undesired compounds.